"Nonchronic drug use was not statistically related to either of the labor supply measures, indicating that light or casual drug use did not lead to negative effects on the labor supply."

Source

French, Michael T., M. Christopher Roebuck, and Pierre Kebreau Alexandre, "Illicit Drug Use, Employment, and Labor Force Participation," Southern Economic Journal (Southern Economic Association: Oklahoma State University, Stillwater, OK, 2001), 68(2), p. 366.